Related Experiment Video
Updated: Feb 24, 2026
Human Circadian Phenotyping and Diurnal Performance Testing in the Real World
Published on: April 7, 2020
Calculating dim light melatonin onset in children: A comparison of four estimation methods
Rebecca C Cox1, Isabella M Sagman2, Lauren E Hartstein3,4
1Department of Psychological and Brain Sciences, Washington University in St. Louis, St. Louis, Missouri, USA.
Insights
This study found that fixed thresholds (3 and 4 pg/ml) and the "hockey stick" method reliably estimate dim light melatonin onset (DLMO) in children. The 2 SD method is less consistent but useful for high melatonin secretors.
Area of Science:
- Chronobiology
- Pediatric Sleep Medicine
- Biomarker Research
Background:
- Dim light melatonin onset (DLMO) is a key circadian phase marker.
- Accurate DLMO estimation is crucial for pediatric sleep research.
- Previous studies have not compared DLMO estimation methods in children.
Purpose of the Study:
- To compare the agreement of four different methods for estimating salivary DLMO in a pediatric population.
- To identify the most reliable methods for DLMO assessment in young children.
Main Methods:
- Salivary DLMO was calculated using four methods: fixed thresholds (3 pg/ml, 4 pg/ml) and individual thresholds (2 SD above baseline, "hockey stick").
- Data were collected from 49 children (mean age 4.40 years).
- Intraclass correlations and pairwise correlations were used to assess agreement and relationships with sleep timing.
Main Results:
- All four methods showed significant intraclass correlations (p < 0.001).
- Strongest agreement was found between the 3 pg/ml, 4 pg/ml, and "hockey stick" methods.
- DLMO estimates from all methods positively correlated with sleep timing (p < 0.001).
- The 2 SD method showed more discrepancy but provided a plausible estimate in a high melatonin secretor.
Conclusions:
- The 3 pg/ml, 4 pg/ml, and "hockey stick" methods offer reliable DLMO estimates in young children.
- The 2 SD method may be valuable for estimating DLMO in children with atypical melatonin secretion patterns.
- Findings support the use of specific methods for accurate circadian phase assessment in pediatric populations.
Abstract:
Dim light melatonin onset (DLMO) is the gold standard circadian phase marker in humans. Although several methods can be employed to estimate DLMO, no research has compared agreement across methods using data from pediatric populations. Here, we compared salivary DLMO calculated using four different methods, including two fixed thresholds (3 pg/ml and 4 pg/ml) and two individual thresholds (2 SD above baseline and the "hockey stick" method) in data from 49 children (M = 4.40 ± 0.66 y, 57% female). Intraclass correlations among the four methods were all significant (p < 0.001), with the strongest agreement observed between the 3 pg/ml, 4 pg/ml, and hockey stick methods. DLMO values from all methods were positively correlated with sleep timing (p < 0.001). Although the 2 SD method was more discrepant from the other three estimation methods on average, it did yield a more plausible DLMO estimate in one individual identified as a high secretor. Overall, our findings suggest the 3 pg/ml, 4 pg/ml, and hockey stick methods provide reliable estimates of DLMO in young children, whereas the 2 SD method may allow a more accurate DLMO estimation in edge cases of high or low melatonin secretors.
